Claude Gelinas

Texturing of thick films on a metallic substrate

Low-temperature melt-texturing of a laminated composite tape was carried out. No reaction or contamination of the superconducting phase was detected and the interface was very clean. The application of the authors procedure for obtaining well-connected textured material is discussed.

Mass transfer in a ErBa2Cu3O7 pellet partially melted in a thermal gradient

Abstract Melt texturing in high thermal gradients promotes the crystallization of oriented RBa2Cu3Ox grains which improves the critical current densities. However, the presence of high thermal gradients induces a transport of material that modifies the composition of the melt and disrupts the crystallization process. In this study, material transfer phenomena have been examined by crystallizing a ErBa2Cu3Ox pellet in a static thermal field. The influence of material transfer on the microstructure of textured pellets has been studied. These microstructures indicate that the material is transferred mainly by thermocapillarity. We also determined that the temperature of the characteristic ridge formed during crystallization was about 892 ± 10°C which corresponds closely to the solidification of the binary and ternary eutectic temperatures.

Interactions of various substrates with melted ErBa2Cu3Ox

The interactions of partially melted Er-Ba-Cu-O superconductors with various substrates including MgO, TiO2, SiC and PSZ were studied with the objective of finding an adequate buffer layer for a nickel-HTSC composite. Bulk ErBa2Cu3Ox pellets were melt-textured on the substrates and the superconductive properties of the composites were assessed by AC susceptibility. In the present paper, microstructure of the textured superconductors and the interfaces are described. Contamination of 123 grains by the various materials and the composition of the reaction products are presented.

Laser processing of plasma-sprayed R-Ba-Cu-O coatings

Thick Y-Ba-Cu-O and Er-Ba-Cu-O coatings were deposited by plasma spraying onto nickel substrates. These plasma-sprayed coatings were laser melted to modify their microstructures. The effects of primary processing conditions, such as linear energy and number of passes, on microstructural modifications were assessed. The microstructure of the as-sprayed coatings was largely transformed to produce a fine Y2O3 dispersion in a Ba-Cu-O matrix. A very low level of coating/substrate interactions can be maintained by appropriate laser processing conditions.

Effect of precursors on the size of 2-1-1 in melt-processed ErBa2Cu3O7−x

Abstract In order to study the influence of the precursors on the size of 2-1-1 inclusions, three types of precursors based on stoichiometric ErBa2Cu3O7−x, were melt-processed: a synthesized powder (SP), a melt-quenched powder (MQP) and a mixture of Er2O3 and Ba-Cu-O compounds (MP). It is demonstrated that a fine dispersion of Er2O3 in a Ba-Cu-O liquid (MP) does not explain the finer 2-1-1 inclusions that form in the MQP material. The refinement of the 2-1-1 phase in MQP samples is attributed to the presence of platinum in the ErBa3Cu2Ox phase found in melt-quenched precursors before melt-processing.